The present invention relates to a method for wireless communication, comprising receiving, by a second serving network, an attach request originated from a user equipment, the attach request carrying a temporary identifier; transmitting, by the second serving network, a request message to a first serving network that previously served the user equipment to obtain a user context from the first serving network according to the temporary identifier carried in the attach request; receiving, by the second serving network, a response message from the first serving network indicating a failure in retrieving the user context; transmitting, by the second serving network in response to the failure, an identity request message to the user equipment, wherein the identity request message includes an identity type indicating an encrypted subscription identity; and receiving, by the second serving network, an identity response from the user equipment including the encrypted subscription identity.